RSX-11

:For the automobile, see Acura RSX.

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RSX-11: A family of real-time operating systems mainly for PDP-11 computers created by Digital Equipment Corporation (DEC), common in the late 1970s and early 1980s, designed for and much used in process control, but also popular for program development.

Related Topics:
Real-time operating system - PDP-11 - Digital Equipment Corporation - 1970s - 1980s

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It existed in many versions:

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• RSX-11/A, C -- small paper tape real time executives.
• RSX-11/B -- small real time executive based on RSX-11/C with support for disk I/O. To start up the system, first DEC DOS was booted, and then RSX-11/B was started by some command that I do not recall. RSX-11/B programs used DEC DOS macros to perform disk I/O.
• RSX-11/D -- evolved into IAS
• RSX-11M -- a multiuser version that was popular on all PDP-11s.
• RSX-11S -- a memory-resident version of RSX-11M used in embedded real-time applications.
• RSX-11M-Plus -- a much extended version of RSX-11M, originally designed to support the multi-processor PDP-11/74, a computer that was never released, but also used widely as a standard operating system on the PDP-11/70. The first version of RSX to include DCL (Digital Command Language).
• RSX-20F --11/40 front end processsor operating system for the DEC KL10 processor. Derived from RSX-11S
• Micro/RSX -- a stripped-down version implemented specifically for the Micro PDP-11, a low-cost multi-user system in a box, featuring ease of installation, no system generation, and a special documentation set.
• P/OS -- A version of RSX-11M-Plus that was targeted to DEC's PRO-300, PRO-350, and PRO-380 line of PDP-11-compatible personal computers.
• DOS/RV, OSRV-SM -- Two names for the clandestine clone of RSX-11M that was produced behind the Iron curtain. This system appeared to be an exact duplicate of RSX-11M save that the prompt was changed in the binary files. According to other sources, RSX-11M source code might have been stolen by the KGB. If read as Cyrillic, the name OSRV is an abbreviation for 'Operatsionnaya Sistema Realnogo(Razdelenija) Vremeni' -- Russian for 'Real Time(Time dividing) Operating System'. Not surprisingly, the six-character string 'OSRVSM' fits nicely in the same 16-bit RADIX-50 word as 'RSX11M'. But, there are differences between RSX and OSRV because of differences between SM and PDP' hardware and recognised by Soviet engineers bugs in RSX. (OSRVM is the next model of OSRV-SM for the SM-1425.) But RSX11M 'patched' for the SM's processor was used more often than rewritten OSRV. That happened because of better work by the RSX-11' re-coders, stability of patched RSX, and a faster update cycle for SM-RSX drivers & patches, made possible by the SM users community. OSRV and RSX driver interfaces are different & incompatible.

Dave Cutler was the project leader for RSX-11M, which was an adaptation of the earlier RSX-11D for a smaller memory footprint. Principles first tried in RSX-11M later appeared in DEC's VMS. Microsoft's Windows NT system is a distant descendent of RSX-11M but is more directly descended from an object-oriented operating system Cutler developed for a RISC processor (PRISM) which was never released. This lineage is made clear in Cutler's foreword to Inside Windows NT, quoted on Neil Rieck's "Windows-NT" is "VMS re-implemented" page.

Related Topics:
Dave Cutler - VMS - Windows NT - PRISM

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RSX-11: Quotes from Cutler ►